Tone generator



Nov. 6, 195] c, w, LARSON 2,573,975

TONE GENERATOR Filed Aug. 1, 1950 FIEL5 37 10 P16. 6. FIG. 2. w 13 4-9 g I ///Z 7 42 V Invenlor Carl W. Larson AH orngys Patented Nov. 6, 1951 TONE GENERATOR Carl W. Larson, Minneapolis, Minn, assignor to Patent Management, Incorporated, Minneapolis, Minn, :a corporation of .Minnesota Application August 1, 1950,:Se1ial No. 176,942

4 Claims. 1

The herein disclosed invention relates to tone generators of the magnetic type for electric organs and has for an object to provide a tone generator in which a closed magnetic circuit is used.

Another object of the invention resides in providin a tone generator in which a toothed wheel "and a smooth-wheel are employed which are disposed adjacent one another in flux conducting relation.

A still further object of the invention resides in providing a tone generator in which a magnetic core is employed having two spaced legs 'formed with poles at the ends of the same "arranged in flux conducting relation with respect tosaid wheels.

Another object of theinvention resides in proriding a permanent magnet between said legs at the other ends of the same and in furtherproviding a coil on one of saidlegs.

A feature of the invention resides "in providing a case for the core open at the rear and containing said coil and magnet and in further utilizing one of said legs as a closure for the rear of the case.

Another object of the invention resides in providing a support disposed adjacent said wheels and having a surface at right angles to the axis of said wheels and in further providing 'a U-shaped guide for said case open at its ends arranged on said surface with the direction of extent of said guide being radial and in which the case-may be slid-radially to vary the lengths of theair gaps between said poles and'wheels.

Other objects of the invention reside in the 1 :novel combination and arrangement of parts and in the details of construction disclosed :in this application.

In the drawings:

:Fig. 1 is an elevational'view of a portion oian electric organ with an embodiment of the invention applied thereto candqdrawn to :an enlarged iscale.

Fig. 2 is a .cross sectional viewxtaken .on line 2-2 or Fig. 1.

Fig. 3 :is-an elevational sectionalview taken on line 33 .of Fig. 1.

'4 is an elevational view of the case and magnet with the spacer and rearleghf the :core removed.

Fig. 5 is :an elevational view of 'the-rear'leg of I xtheicore.

The structure disclosed in this application for 2 patent consists of a plate serving as a support and through which a shaft extends. On this shaft is mounted atoothed wheel and a smooth wheel in flux conducting relation with respect to one another. A guide U-shaped in form and open at its ends is attached to the plate with the direction of its extent being radially with leg which extends through all three partitions,

intermediate said walls and having one end pro- 'jectin outwardly beyond the adjacent partition and "formed with a pole adapted to be disposed adjacent the toothed wheel. The core has another leg which forms a closure for the rear of the case and which is also formed with a projecting end having a pole disposed adjacent the smooth wheel. Between the other ends of said legs is disposed a permanent magnet situated in one of said compartments while in the other compartment is a coil encircling said first named leg. A spacer disposed upon the exterior of said closure separates the same from said plate. Adjustment of the case along said guide varies the length of the air gap between said poles and wheels.

For the purpose of illustrating the invention :a support II ll has'been shown which is in the form of a plate :and which constitutes a part of an :material such :as "brass, bronze or certain types of stainless steel and is iournalled in bearings .not shown and which-are mounted on supporting structure with reference to which the plate Iii is fixed. The axis of the shaft I2 is at right angles-to the surface I3of plate I 0.

On the side of the surface I3 of plate II] are mounted on shaft -I2,:a wheel I4 having a smooth circumferential face I5, and a wheel I6 having :a number of teeth I"! equally spaced and disposed at the periphery of said wheel. The wheels I4 and :6 are constructed of iron, steel or some other suitable flux conducting material and are arranged close toone another so as to be in mag netic flux conducting relation. Collars I8 and IS on said shaft I2 hold the wheels I4 and IS in proper position on said shaft with relation to 3 the plate In and other parts on the shaft. These collars are also of material similar to shaft l2.

Cooperating with the wheels 14 and I6 is a magnetic unit 20. This unit includes a case 2|, U-shaped in form, which is preferably bent up from metal and which has a front wall 22 and side walls 23 and 24. Partitions 25 and 26 extend across the walls 22, 23, and 24 and close the ends of the case. An intermediate partition 21 also extends across the walls of the case and forms in it two compartments 28 and 29.

and are somewhat shorter than the widths of the walls 23 and 24. 1

The magnet unit as further comprises a core 30 which includes two spaced legs SI and 32.-

The leg 3! is in the form of a bar and extends through all of the partitions 25, 2'! and 2e intermediate the walls 22, 23 and 24 and the rear edges of the walls 23 and 24. This bar has one end extending outwardly beyond-the partition 26 and constructed to form a pole 33 for cooperation with the teeth ll of the wheel l5. On this leg is wound a coil 24 which is disposed in compartment 29. is in the form of a plate and is shown in detail in Fig. 5. The width of this plate is equal to the distance between the walls 23 and 24 so that said plate fits in between said walls and rests on the partitions 25, 26 and 2?. Ears 35 on said plate engage the ends of said walls and prevent longitudinal movement of the plate relative to the case. One end of the leg 32 projects outwardly beyond the partition 2% and is constructed to provide a pole 36 which is adapted to cooperate with the surface l5 of wheel 4. The other end of this plate has a lug 37 formed on the same which has a hole l33 in it. This con struction may be used for a purpose to be presently described. A permanent magnet 42 is disposed between the two legs at and 32 at the ends thereof opposite the poles 33 and 36 and is disposed in the compartment 28 fitting snugly between the partitions 25 and 21. This magnet is polarized in the direction between the two legs and forms a yoke therebetween. This magnet, the partitions 25, 26 and 21, the leg 3| and coil 34 are all firmly cemented together and to the case 2!. Ears 43 on the ends of wall 22 of case 2i extend over the partitions 25 and 25 and. further assist in holding the parts assembled.

The magnet unit 28 is adjustably mounted in a guide 38 best shown in Figs. 1 and 2. This guide is constructed from sheet metal and is U-shaped in form having a front wall 42; and side walls 4i and 4.2, being open at the top, bottom and the back. Flanges 44 and 45 extend outwardly from the walls 4! and 42 and are adapted to overlie the surface I3 of plate H3. The flange Ad is secured to the plate ill by means of rivets 46 while the flange 45 may be clamped up against the said plate by means of a screw 47 passing through said flange and screwed into said plate. The entire magnet unit 20 is adapted to be received in the guide 38 with the walls 22, 23 and 24 disposed adjacent the walls 42, d! and 42 a spacer as best shown in Figs. 3 and 6 is disposed between the leg 32 and the surface I 3 of plate ID. This spacer is of the exact form of the leg 32 except that it does not have a pole or lug but does have ears 49 similar to the ears 35. This spacer is received between the walls 23 and 24 of the case 2! and said ears 49 engage the ,endsof said walls. With the unit All of the" partitions are constructed of insulatin material The other leg 32 of the core 39 4 30 properly installed in the guide 38, pole 33 is in the path of movement of the teeth ll of wheel I6 and pole 36 lies opposite the surface I5 of wheel l4. By sliding the unit along said guide through engagement with lug 3! the length of the air gaps between the poles and wheels may be adjusted as desired. When the unit is properly adjusted tightening of screw 41 holds the parts in proper position.

If desired several magnet units may be employed cooperating with a single pair of wheels. .Where they are desired in pairs another guide 59' would be used which is similar to the guide 38. In such case the flange 5| of said guide may be integral with the flange 44 of guide 38 and only one set of'rivets used for both guides.

The use of the invention is obvious. The magnet units may be adjusted by loosening screw 41 and sliding the unit along the guide 38. Tightening the screw locks the parts together and also clamps the legs 3| and 32 against the magnet 42.

The invention has numerous advantages. The device is extremely simple and is positive in action. With the closed magnetic circuit less amplification is reouired and better tone quality results. The units can be constructed at a nominal expense, and are compact in size. The units are readily replaceable and adjustable to procure different length air gaps and the attendant advantages thereof.

What is claimed to be new and desired to be protected by Letters Patent is:

1. In a tone generator, a toothed wheel and a smooth wheel disposed in'magnetic flux conducting relation adjacent each other I and mounted on a revolvable shaft, a U-shaped case openat the back and at its ends and having side .walls and a front wall, partitions at the ends of the case closing the ends of the same, a partition intermediate said first named partitions and extending across the'case and dividing the same intotwo compartments, a magnetic core including a leg extending through one of said first named partitions and through said intermediate partition and spaced'from the walls of the case, said core having'a second leg disposed at the rear of the case and forming a rear wall for'the case, poles on corresponding ends of the legs of the core and projecting outwardly beyond the portion adjacent such ends of the legs, means for supporting said poles in flux conducting relation with respect to said wheels, a permanent magnet disposed'between the other ends of the legs and disposed inthe compartment in which said ends of the legs are situated, and a coil wound on said first named leg and disposed in the'other compartment and energized by variation influx passing through the air gaps between said poles and wheels and produced by rotation of said shaft.

2. In a tone generator, a toothed wheel and a smooth wheel disposed in magnetic flux conducting relation adjacent each other and mounted on a revolvable shaft, a plate forming a support and disposed .at right angles to said shaft and adjacent one of said 'wheels,'a U- shaped guide open at its ends and attached to said plate, with the longitudinal direction of extent of said guide being disposed in a radial direction with reference tosaid wheels, a case insertable into said guide and slidable along. the

same in a radial direction, a magnet carried by said case and having two legs extending; in a radial direction, poles on the endsof'said" legs and adapted to be disposed, one in flux conducting relation with said toothed wheel and the other in flux conducting relation with said smooth wheel, and a coil on one of said legs, the air gaps between said poles and wheels being variable by moving said case along said guide.

3. In a tone generator, a toothed wheel and a smooth wheel disposed in magnetic flux conducting relation adjacent each other and mounted on a revolvable shaft, a plate forming a support and disposed at right angles to said shaft and adjacent one of said wheels, a U-shaped guide open at its ends and attached to said plate, with the longitudinal direction of extent of said guide being disposed in a radial direction with refer ence to said wheels, a case U-shaped in form having a front wall and side walls and insertable into said guide through the open end thereof and slidable along said guide, partitions at the end of the case, extending across said walls, a magnetic core including a leg extending through one of said partitions intermediate said walls, a closure for the rear of said case and forming another leg of said core and projecting outwardly beyond said case at the same end as first named leg, poles on the projecting ends of said legs and disposed in flux conducting relation with said wheels and a spacer between said last named leg and said plate.

4. In a tone generator a toothed wheel and a smooth wheel disposed in magnetic flux conducting relation adjacent each other and mounted on a revoluble shaft, a supporting plate, a U-shaped guide having a front wall, side walls and flanges extending outwardly from said side walls and overlying said plate, screws extending through said flanges and engaging said plate to hold the guide attached to the plate, a case disposed within said guide, a magnet carried by said case and having legs extending outwardly therefrom and formed with poles, means for holding said wheels in flux conducting position with reference to said poles, said guide guiding said case and magnet for movement toward and from said wheels, said screws serving to draw said flanges toward said plate and to clamp the case in po sition between said front wall of the case and the plate.

CARL W. LARSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 599,942 Lamme Mar. 1, 1898 1,137,544 Severy Apr. 27, 1915 2,205,669 Pye June 25, 1940 2,355,047 Bennett Aug. 8, 1944 

